will we be able to interact with those who are in
different levels than us in Heaven?

Answer by Fr. John Echert on 1/15/2013:

Yes, if by levels you have in mind my earlier post that among the saints of Heaven, not all are equal in their degree of charity and therefore their happiness. This is not a class distinction, but a matter of how much in love with God each person is. By analogy, in marriages there are those who are deeply in love with each other and others not so much in love: which married couples are likely happier?